Conventional vehicle headlamps may include upper and lower optical units each utilizing a semiconductor light emitting device, such as those disclosed in Japanese Patent Application Laid-Open No. 2005-108554 (JP4044024B or U.S. Patent Publication No. 2005/0068787A1 corresponding thereto) and Japanese Patent Application Laid-Open No. 2007-109493 (JP4615417B or U.S. Patent Publication No. 2007/0086202A1 corresponding thereto).
FIG. 1 is a vertical cross-sectional view of a conventional vehicle headlamp 200 described in Japanese Patent Application Laid-Open No. 2005-108554.
As shown in the drawing, the vehicle headlamp 200 can have an optical axis AX extending in the front-to-rear direction and include a projection lens 210 disposed on the optical axis AX and having a rear-side focal point F, a first optical unit 220 disposed behind the projection lens 210 and facing upward, a second optical unit 230 disposed behind the projection lens 210 and facing downward, and a shade 240 disposed between the upper and lower optical units 220 and 230. The first optical unit 220 can include a semiconductor light emitting device 221 and a reflecting surface 222 while the second optical unit 230 can include a semiconductor light emitting device 231 and a reflecting surface 232.
In the vehicle headlamp 200 described in Japanese Patent Application Laid-Open No. 2005-108554 with the above configuration, the light provided by the second optical unit 230 (or the semiconductor light emitting device 231) can be converged at or near the rear-side focal point F of the projection lens 210 while a part thereof is shaded by the shade 240. The light passing through the projection lens 210 can be projected forward to form a high-beam light distribution pattern in the illumination direction thereof.
FIG. 2 is a vertical cross-sectional view of a vehicle headlamp 300 described in Japanese Patent Application Laid-Open No. 2007-109493.
As shown in the drawing, the vehicle headlamp 300 can have an optical axis AX extending in the front-to-rear direction and include a projection lens 310 disposed on the optical axis AX, a first optical unit 320 disposed behind the projection lens 310 and facing upward, a second optical unit 330 disposed behind the projection lens 310 and facing downward, and a shade 340 disposed between the upper and lower optical units 320 and 330. The projection lens 310 can include a center lens portion 311 disposed on the optical axis AX and a peripheral lens portion 312 disposed below the center lens portion 311. The first optical unit 320 can include a semiconductor light emitting device 321 and a reflecting surface 322 while the second optical unit 330 can include a semiconductor light emitting device 331 and a reflecting surface 332.
In the vehicle headlamp 300 described in Japanese Patent Application Laid-Open No. 2007-109493 with the above configuration, the light provided by the second optical unit 330 (or the semiconductor light emitting device 331) can be converged at or near the rear-side focal point F of the peripheral lens portion 312 of the projection lens 310 while the light is not shaded by the shade 340. The light passing through the peripheral lens portion 312 of the projection lens 310 can be projected forward to form a high-beam light distribution pattern in the illumination direction thereof.
In the vehicle headlamp 200 described in Japanese Patent Application Laid-Open No. 2005-108554, the produced high-beam light distribution pattern can include only the upper part of the projected light due to the lower part of the light shielded by the shade 240. Therefore, the vehicle headlamp 200 can form a high-beam light distribution pattern with insufficient luminous intensity, meaning that the high-beam light distribution pattern is formed with less design freedom.
In the vehicle headlamp 300 described in Japanese Patent Application Laid-Open No. 2007-109493, the produced high-beam light distribution can include the light without being shielded by the shade 340. However, as the projection lens 310 has a front surface 310a with a step A formed between the center lens portion 311 having a front surface 311a and the peripheral lens portion 312 having a front surface 312a, the resulting lens surface is a discontinuous lens surface. This prevents an observer from visually recognize the projection lens 310 as a single lens with less aesthetic features.